1. Field of the Invention
This invention relates to a vehicle body and a method of manufacturing vehicle bodies more particularly, to railway and other track-guided vehicle bodies, including bodies for monorail and mag-lev (magnetic levitation) vehicles.
2. Description of the Prior Art
Conventionally, railway vehicle bodies have been formed of steel, by shaping thin steel plates and welding the plates to provide the sides, roof, floorplate and end of the body. One example of such a process is shown in JP-B-63-12027, in which the body side is formed by first welding together planar sheets previously cut to shape, then bending the side to the desired shape, and then spot welding horizontal and vertical frame members to the sheet side. The frame metals are channels, so that a box structure is produced for each frame member, with the steel used in such a process having a typical thickness of 1.6 mm.
A particular problem which arises with the use of steel in this manner is that the welding of the frame members to the sheet side causes distortion of the thin outer plates, and this distortion must be removed after completion of the structure. A great deal of time and labor is necessary to remove the distortion. The occurrence of the distortion during the production of the structure can be prevented, in principle, by bonding the frame members to the plates while tension is applied to the plates, but an apparatus for applying tension is required and the production process is complicated.
It is also known to form railway vehicle bodies from extruded metal plates having integral ribs on the inside faces, with the extruded metal sections or plates being typically formed of a light metal, particularly aluminium or aluminium alloy. An example of a railway vehicle so constructed is described in "Light Metal Railway Vehicle Committee Report No. 3", 1978 Japanese Railway Vehicle Industry Association, pages 70-72. This body has sides comprising seven sections welded together along vertical weld lines, with each section being itself formed of a number of elements of different shapes, welded together, and the ends are similarly formed. The roof is partly formed of elongate plates having integral ribs welded together at overlapping edges, with ribs being provided at these edges. The welding is conducted from the outside of the plates and is groove welded with a backing plate integral with one plate, i.e. the plates overlap. Japanese Utility Model Publication No. 57-42128 illustrates a similar construction of a railway vehicle body side.
In these structures formed of extruded plates, the arrangement of the plates for welding is complicated, and automation cannot be achieved. To avoid the occurrence of distortion in the plate surface, the thickness of the plate is increased, increasing the weight of the vehicle, even though the plates are made of light metal.